Metal carbonate initiator and method for polymerizing isocyanates using the same

Abstract

Disclosed herein is a metal enolate initiator for polymerizing isocyanates and a method for polymerizing isocyanates by anionic polymerization using the same, in which the initiator forms a cluster upon the initiation and protects stability of terminal anions at the end of the chain to cause controlled polymerization, thus preventing depolymerizaton and improving reaction time and efficiency without the use of a separate additive.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of Korean Patent Application No. 10-2006-0069998, filed on 25 July, 2006, the entire disclosure of which is hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an initiator for polymerizing isocyanates, more particularly, to a metal enolate initiator for polymerizing isocyanates and a method for polymerizing isocyanates by anionic polymerization using the same, in which the initiator forms a cluster upon the initiation and protects stability of terminal anions at the end of the chain to cause controlled polymerization, thus preventing depolymerizaton and improving reaction time and efficiency without the use of a separate additive.[0004]2. Description of Related Art[0005]In general, polyisocyanates are prepared by anionic polymerization [Bur, A. J.; Fetters, L. J. Chem. Rev. 1976, 76, 727.]. Typically, the anionic polymerizatio...

AI Technical Summary

Benefits of technology

This approach enables the production of polyisocyanates with controlled molecular weight and monodispersity, reducing reaction time and improving initiation efficiency, while avoiding the use of separate additives and extreme conditions.

Problems solved by technology

As a result, it is difficult to control the molecular weight of a polymer and to obtain a monodispersed polymer.

Moreover, the anionic polymerization of isocyanates requires extreme reaction conditions such as high vacuum and low temperature due to a high reactivity of an isocyanate monomer.

A method for controlling the polymerization of isocyanates has been a very difficult problem for numerous researchers, and extensive research aimed at polymerizing isocyanates with a controlled structure by the anionic polymerization has continued to progress.

Although this polymerization offered an improved yield, it was difficult to control the molecular weight and to obtain a monodispersed polymer, and thereby it was impossible to find a condition for living polymerization.

Meanwhile, another difficulty raised in the polymerization of isocyanates is solubility to a solvent.

Since the solubility of a monomer and a polymer obtained at low temperature to dimethylformamide (DMF), a commonly used solvent, is not good, the molecular weight distribution becomes broader and the yield decreases.

As a result, the yield was improved, but there was no noticeable improvement in the molecular weight distribution.

In this case, however, it was observed that the formation of dimers and trimers became more serious.

However, there were still some drawbacks in that the yield was as low as 32% to 70%, and the molecular weight distribution was as uncontrollable as 2 to 4.

In this case, however, there were also some drawbacks in that a catalyst system, which was very complex and expensive, should be used for the coordination polymerization, the yield was still lower than 100%, and copolymerization with other monomers was not possible.

However, they did not take into considerations of various parameters for living conditions and for structure-control, such as reaction time, counter ion, and the like.

However, it has a difficulty in the process due to the use of an additive.

However, it has some drawbacks such as long reaction time and low initiation efficiency due to a low reactivity of the amidate anion.

As described above, according to the conventional methods for preparing polyisocyanates, it is difficult to control the molecular weight due to the formation of dimers or trimers, and they have some drawbacks such as a difficulty in the process due to the use of an additive, deterioration of reaction yield due to the low reactivity, and a broad molecular weight distribution.

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